1. Field of the Invention
The present invention relates to a cored yarn having, as inner fibers (core), stretchable filament yarns such as spandex (polyurethane elastic yarns) and, also, relates to a method and apparatus for producing such a cored yarn.
2. Description of Related Art
Various types of cored yarns, having, as a core, stretchable filament yarns such as spandex and having, as an outer part, natural fibers such as wool or cotton (staple fibers), have here-to-fore been proposed. Such a type of core yarn is intended for imparting to the yarn a stretchability of the spandex as well as a soft touch of the natural fibers and is mainly targeted to be used for a knit wear. In order to produce such cored yarn, a fine spinning of wool or cotton is carried out in such a manner that the core is mixed with a roving from a rear side of front rollers. The stretchable filaments mixed with the roving under drafting operation from the front rollers is subjected to a twisting operation together with the drafted outer fibers constructed by wool or cotton and is subjected to a winding operation, resulting in a formation of a cop.
In the conventional cored yarn have, as a core, spandex, a use of wool as outer fibers may case a soft touch to be easily lost due to a shrinkage as occurred by a washing. Thus, a selling of the product must necessarily be made together with a warning for prohibition of a washing, which may likely cause the products not to be accepted in the market.
Furthermore, in the prior art cored yarn, a condition, that a core (inner fibers) is completely covered by the outer fibers, is not always maintained. Namely, any control of the core is not done, resulting in an exposure of the core yarn to the outer layer at positions along the length of the yarn. In such a situation, the yarns provide locally differently sparkled portions, which makes a knitted fabric to be defective one and which also makes a dyed fabric to be defective one since the sparkled portions are colored differently.
An object of the present invention is for overcoming the above mentioned difficulties and is for providing a construction of a cored yarn of an increased washability, while being capable of maintaining a condition that the core is always fully covered by the outer layer.
According to the first invention, a cored yarn is provided, which comprises inner fibers formed by stretchable filament yarns and outer fibers formed by non-shrink treated wool.
By the filament yarns as a core and the wool as the outer layer according to the present invention, a knitted fabric having both of stretchability as well as soft touch is obtained, and the non-shrink treatment of the wool allows an washing to be practiced, thereby obtaining a garment of an enhanced handleability.
According to the second invention, a cored yarn is provided, which comprises inner fibers formed by stretchable filament yarns and outer fibers formed by short fibers, said outer fibers comprising two parts which substantially separately twisted, said stretchable filament yarns being located intermediate between said separately twisted parts constructing said outer fibers which are twisted. The outer fibers may be constructed by wool, which is preferably subjected to non-shrink treatment, while the inner fibers may be constructed by a spandex of a heat set type. Furthermore, the spandex may be the one which, at its outer layer, lapped by synthetic fiber filaments.
According to the third invention, a cored yarn is provided, which is produced by drafting, in parallel, a plurality of rovings and twisting them together, while combining, from a rear side of front rollers, a stretchable filament yarn to said drafted rovings, while guiding said stretchable filament yarn so that the latter is maintained centrally between said drafted rovings, so that the stretchable filament yarn is positioned centrally, around which portions of the yarn from the rovings are twisted.
In the third invention, in order to produce the cored yarn, said two rovings, which become the outer fibers short fibers (staple fibers), are simultaneously fed to the drafting part, while the stretchable filament yarns which become the core yarn are introduced from the rear side of the front roller in such a manner that the filaments yarns are guided to the intermediate position between the two rovings which are under drafting operation. As a result, the two rovings emerged from the front roller are, first, subjected to a separate twisting for causing their fibers to be twisted each other and are, then, integrated to a single yarn in such a manner that the stretchable filament yarns as the core are located intermediate between the integrated portions of (outer fibers) which are twisted. As a result, a brightly colored yarn of reduced fluff can be produced and a condition is always maintained in such a manner that the stretchable filament yarns as the core are fully covered by the wool as the outer layer. As a result, the core fibers are prevented from being emerged outwardly, so that an occurrence of defects during knitting process or dyeing process is less likely. Finally, the wool constructing the outer layer is preferably subjected to the non-shrink treatment, and the inner fibers may be a spandex of a heat set type.
According to the fourth invention, a method is provided for producing a cored yarn, said method comprising the steps of:
providing drafting device having back rollers and front rollers between which a drafting zone is created;
feeding a plurality of rovings, under a parallel condition, to said back rollers for causing the rovings to be subjected to a drafting operation at the drafting zone;
feeding, from the front rollers, filament fibers so that the filament fibers are combined with the drafted rovings;
guiding the filament fibers so that the feeding of the filament fibers are substantially always done at a central position between the plurality of the rovings, and;
twisting and taking-up the drafted roving together with the filament fibers for obtaining a cored yarn wherein the filament fibers as a core is covered by the twisted rovings as outer fibers.
In the operation of the fourth invention, a plurality of rovings are fed, in parallel, to the draft part, and a guiding of the filament fibers as the core is done in such a manner that the filament fibers are always fed to the central position between the rovings which are fed in parallel. As a result, an advantage is obtained that a condition is always and steadily obtained that the filament fibers as the core is fully covered at the center of the outer fibers. As a result, the filament fibers as the core is prevented from being displaced to the outer layer and, in a subsequent process, an occurrence of defects at a knitting or weaving or dyeing speck is substantially completely prevented.
According to the fifth invention, system for producing a cored yarn, said system comprising:
a drafting unit comprising front rollers and back rollers, between which a drafting zone is created for executing a drafting operation of rovings as outer fibers;
a collector arranged at the inlet of the front rollers for collecting the rovings and guiding the them to the front rollers, the collector having a width which allows the rovings to be fed to the front roller while keeping substantially separated condition;
a feeder of the filament fibers to the front rollers, the filament fibers being combined with the drafted rovings;
a guide of the filament fibers to the front roller, said guide being harmonized with the lateral movement of the rovings at the front roller in such a manner that the filament fibers is always fed to the rovings at a central position between the rovings, and;
a spindle by which the drafted rovigns are twisted and taken-up together with the filament fibers, thereby obtaining a cored yarn wherein the filament fibers as a core is covered by the twisted rovings as outer fibers.
In the operation of the fifth invention, a plurality of rovings during the drafting is maintained in their paralleled condition at the collector and are twisted and taken up from the front rollers. The guide member for guiding the filament fibers is mounted to the collector. As a result, even in a movement (displacement in the lateral direction) of the collector, the guide member is always integrally moved with respect to the collector, so that a positional relation-ship of the filament fibers between intermediate between the rovings is always maintained. As a result, a condition is constantly and steadily obtained that the filament yarns as the core are completely and centrally covered by the outer layer fibers. In the fifth invention, a very simplified construction, that the guide member is fixedly connected to the collector, can solve the problem and, therefore, is advantage since the aim can be realized at a highly reduced cost.